Tuesday, 2 June 2020

2075-Solution of Computational Course (Computer Science) : Short Answer Question

Short Answer Question


Attempt any FIVE questions.


4) Define logic gate. How XOR and XNOR gate work? (1+5)

Ans:
Logic gates are electronic circuits that operate on one or more input signals to produce standard output signal. They are the building blocks of all the circuits in a computer. Some of the most basic and useful logic gates are AND, OR, NOT, NAND and NOR gates.

XOR gate:
The XOR (exclusive OR) gate acts in the same way as the logical “either/or”. The output is “true” if either, but not both of the inputs are “true”. The output is “false” if both inputs are “false” or if both inputs are “true”. 


Truth table for XOR gate:
Input 1
Input 2
Output
0
0
0
0
1
1
1
0
1
1
1
0


XNOR gate:
The XNOR (exclusive NOR) gate is a combination XOR gate followed by an inverter. The output is “false” if either, but not both of the inputs are “true”. The output is “true” if both inputs are “false” or if both inputs are “true”.
Truth table for XNOR gate:
Input 1
Input 2
Output
0
0
1
0
1
0
1
0
0
1
1
1


5) How computers can be classified based on working principle? (6)

Ans:
On the basis of work, computers can be classified in three categories as:
  1. Analog computer
  2. Digital computer
  3. Hybrid computer
  1. Analog computer - An analog computer is the special purpose computer. It can measure physical value (i.e. continuous flow of data) like voltage, current, temperature, pressure, etc. All operations in the analog computer are performed in parallel. Analog computers are used for scientific and engineering purposes. Examples of analog computer are (i) speedometer in car or motorcycle (ii) thermometer (iii) seismograph that measures earthquake.
  1. Digital computer - Digital computer are the general purpose computers. They use discrete data like letter, numbers, symbols. They represent discrete data in binary digits either 0 or 1. Digital computers work on binary digits . All operations in the digital computer are performed in sequential, one step at a time. They are mostly used in different sectors for performing variety of tasks.
  1. Hybrid computers - Hybrid computers are the special purpose computers. They have the capabilities of both analog computer and digital computers.  Hybrid computers can accept input in analog form, process data digitally and provide output in either digital or analog form. They are used in industrial application, airplanes, ships, hospitals and in scientific research centers. Eg. ECG, halter monitoring machine, ultrasound machine, CT-scan machine, etc.


6) What are the functions of operating system? (6)

Ans:
An operating system is a collection of programs that acts as an interface between a user of a computer and the computer hardware. The purpose of an operating system is to provide an environment in which a user may execute the programs.

The different functions of operating system are:
  1. Security - The operating system uses password protection to protect user data and similar other techniques. it also prevents unauthorized access to programs and user data.
  2. Control over system performance - Monitors overall system health to help improve performance. Records the response time between service requests and system response to have a complete view of the system health.
  3. Job accounting - Operating system keeps track of time and resources used by various tasks and users, this information can be used to track resource usage for a particular user or group of user.
  4. Error detecting aids - Operating system constantly monitors the system to detect errors and avoid the malfunctioning of computer system.
  5. Coordination between other softwares and users - Operating systems also coordinate and assign interpreters, compilers, assemblers and other software to the various users of the computer systems.
  6. Memory management - The operating system manages the Primary Memory or Main Memory. Main memory is a fast storage and it can be accessed directly by the CPU. For a program to be executed, it should be first loaded in the main memory.
  7. Processor management - In a multi programming environment, the OS decides the order in which processes have access to the processor, and how much processing time each process has.
  8. Device management - An OS manages device communication via their respective drivers. It keeps tracks of all devices connected to system


7) Define computer network. Discuss some transmission media. (2+4)

Ans:
A computer network is a group of computers that use a set of common communication protocols over digital interconnections for the purpose of sharing resources located on or provided by the network nodes. The interconnections between nodes are formed from a broad spectrum of telecommunication network technologies.
There are 3 types of computer networks based on the size. They are:
  1. Local Area Network (LAN)
  2. Metropolitan Area Network (MAN)
  3. Wide Area Network (WAN)
Transmission media is a pathway that carries the information from sender to receiver. We use different types of cables or waves to transmit data. Data is transmitted normally through electrical or electromagnetic signals. There are 2 types of transmission media. They are:
  1. Bounded or guided transmission media
  2. Unbounded or unguided transmission media
Bounded or guided transmission media
It is the transmission media in which signals are confined to a specific path using wire or cable. The types of bounded/guided media are:
  1. Twisted pair cable which is further categorized into a) Unshielded twisted pair cable and b) Shielded twisted pair cable
  2. Coaxial cable
  3. Fiber optic cable
Unbounded or unguided transmission media
Unbounded or unguided or wireless transmission media sends the data through air (or water), which is available to anyone who has device capable of receiving them. There are 2 types of unbounded or unguided or wireless transmission media. They are:
  1. Radio transmission
  2. Microwave transmission


8) Why IP address is used in internet? What is the function of domain name system? (2+4)

Ans:
An Internet Protocol (IP) address is an identifying number for network hardware connected to a network. Having an IP address allows a device to communicate with other devices over an IP-based network like the internet.Devices on a network are differentiated from one another through IP addresses. The computer uses DNS servers to look up a hostname to find its IP address.
For example, when you enter a website URL such as www.tribhuvan-university.edu.np into a browser, your request to load that page is sent to DNS servers that look up the hostname of tribhuvan-university.edu.np to find its corresponding IP address. Without the IP address, the computer has no clue what it is that you're after.

An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. The DNS can be quickly and transparently updated, allowing a service's location on the network to change without affecting the end users, who continue to use the same hostname. Users take advantage of this when they use meaningful Uniform Resource Locators (URLs) and e-mail addresses without having to know how the computer actually locates the services.

An important and ubiquitous function of DNS is its central role in distributed Internet services such as cloud services and content delivery networks. When a user accesses a distributed Internet service using a URL, the domain name of the URL is translated to the IP address of a server that is proximal to the user. The key functionality of DNS exploited here is that different users can simultaneously receive different translations for the same domain name. This process of using the DNS to assign proximal servers to users is key to providing faster and more reliable responses on the Internet and is widely used by most major Internet services.


9) Discuss various elements of multimedia. (6)

Ans:
Multimedia is any mixture of text, graphics, art, sound, animation and video with links and tools that let the person navigate, interact and communicate with computer.

The different elements of multimedia are:
  1. Text - Text is by far the most media type in computing applications. Most multimedia system use a combination of text and other media to deliver functionally. Text in multimedia systems can express specific information contained in other media items.
  2. Images - Digital image files appear in many multimedia applications. Digital photographs can display application content or can alternatively form part of a user interface. Interactive elements, such as buttons, often use custom images created by the designers and developers involved in an application.
  3. Audio - Audio files and streams play a major role in some multimedia systems. Audio files appear as part of application content and also to aid interaction. Audio formats include MP3, WMA, Wave, MIDI and Real Audio.
  4. Video - Digital video appears in many multimedia applications, particularly on the web. As with audio, websites can stream digital video to increase the speed and availability of playback. Common digital video formats include Flash, MPEG, AVI, WMV and QuickTime.
  5. Animation - Animated components are common within both Web and desktop multimedia applications. Animations can also include interactive effects, allowing users to engage with the animation action using their mouse and keyboard. The most common tool for creating animations on the web is Adobe Flash.



10) Define firewall. Convert (1100111)2 to equivalent octal and hexadecimal form. (2+2+2)

Ans:
A firewall is a network security device that monitors incoming and outgoing network traffic and permits or blocks data packets based on a set of security rules. Its purpose is to establish a barrier between your internal network and incoming traffic from external sources (such as the internet) in order to block malicious traffic like viruses and hackers.

Firewalls carefully analyze incoming traffic based on pre-established rules and filter traffic coming from unsecured or suspicious sources to prevent attacks. Firewalls guard traffic at a computer’s entry point, called ports, which is where information is exchanged with external devices.

Firewalls can either be software or hardware, though it’s best to have both. A software firewall is a program installed on each computer and regulates traffic through port numbers and applications, while a physical firewall is a piece of equipment installed between your network and gateway.

Conversion from binary to octal:
Step-1 : Divide the binary digits into group of three (starting from the right),
Step-2 : Convert each group of three binary digits to one octal digit.
Example,
Step no.
Binary number
Octal number
1
11001112
12 1002 1112
2
11001112
184878
3
11001112
1478



Conversion from binary to hexadecimal:
Step-1 : Divide the binary digits into group of four (starting from the right),
Step-2 : Convert each group of four binary digits to one hexadecimal digit.
Example,
Step no.
Binary number
Octal number
1
11001112
1102 01112
2
11001112
616716
3
11001112
6716



Therefore, (1100111)2 = (147)8 = (67)16
Posted by at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)